1.0 Overview
The HF Scientific CLX uses a communication protocol called Modbus. A company called
Modicon, for use with their programmable controllers, developed the Modbus protocol.
Since that time Modbus has evolved into common communication protocol in industry.
The communication method involves using a master-slave technique, in which there is one
master and several slaves. The CLX is a slave device. Only the master can initiate queries.
These queries are directed to an individual slave device and the appropriate slave responds
with the requested data.
A broadcast message can be sent to all slaves. The slave devices do not answer these
broadcasts.
There are two transmission modes. These modes are known as RTU (Remote Terminal
Unit) and ASCII (American Standard Code for Information Interchange).
The CLX can be setup in a network of up to 255 slave devices. Each device must have a
different address (1-255). The CLX can be set for either RTU or ASCII mode.
CLX Modbus (8/06)
Rev. 1.2
1
2.0 Electrical Connections
All of the electrical connections to the instrument are made at the termination area, which
is located on the portion of the instrument. The connections are labeled and are self-
descriptive (see Figure 1). Please follow all local and government recommendations and
methods for installation of electrical connections to and between the instrument and other
peripheral devices.
Plugs are inserted into cable bulkheads when shipped, to ensure a watertight seal. These
plugs should be removed and discarded as required when cabling to this connection.
The bulkhead will accept cable diameters from 5.8mm (.230 in.) up to 10 mm (.395 in.).
The terminals are designed to accept wires in the range of 14-28 AWG. All wires should
be stripped to a length of 6 mm
It is the user’s responsibility to assure that the watertight seal is maintained after the
terminal box has been wired for operation. If any of the bulkheads are not tightened
properly around a cable or plug, the ratings of the instrument will be jeopardized and there
is a possibility of creating a shock hazard.
Note: Only qualified electricians should be allowed to perform the installation of the
instrument as it involves a line voltage that could endanger life.
CAPTIVE SCREW
HIGH VOLTAGE C OVER
ALARMS
BULKHEAD
COMMUNICATION
BULKHEAD
POWER
BULKHEAD
POWER
TERMINAL
BLOCK
POWER CABLE
STRAIN RELEIF
ANC HOR
ALARM # 2
TERMINAL
BLOCK
ALARM # 1
TERMINAL
BLOCK
RS- 485
TERMINAL
BLOCK
4- 20mA
TERMINAL
BLOCK
Figure 1: Electrical Connections for the Instrument
CLX Modbus (8/06)
Rev. 1.2
2
2.1 RS-485 Connection
The RS-485 half-duplex (2-wire) digital interface operates with differential levels that are
not susceptible to electrical interferences. This is why cable lengths up to 3000 ft can be
implemented. The last device on every bus may require a 120-ohm termination resistor to
eliminate the possibilities of signal reflection on the line. Do not run RS-485 cables in the
same conduit as power.
Ensure each instrument is not powered when connecting the RS-485 line. To prevent
damage to the instrument, ensure that power is disconnected prior to making connections.
CLX Modbus (8/06)
Rev. 1.2
3
3.0 Operation
3.1 Configuring the RS–485 Port
The CLX is equipped with an RS-485 port which operates in one of three ways (see the
operator’s manual for more information).
Select the correct baud rate (1200, 2400, 4800, 9600, or 19200) for operation of the I/O
port by pressing the t or u buttons to change the displayed baud rate.
Press the ↵ button to continue on and select the desired instrument address (1-255) using
the t or u buttons. Once the selection is satisfactory, press the ↵ button.
Select the operating mode either ASCII or RTU using the t or u buttons. Press the
MODE key to complete the Modbus setup.
CLX Modbus (8/06)
Rev. 1.2
4
3.1 Configuring the RS–485 Port (continued)
For Modbus some applications, especially involving the ASCII operation mode, it may be
necessary to set a different protocol than the default setting (8 bits, 1 stop bit, no parity).
Menus are available for this in the Extended Settings portion of the configuration
CONFIG mode.
While in the CONFIG mode, press the ↵ button, several times until the Extended Settings
is as shown below. Select On using the t or u buttons.
Press the ↵ button a few times until the menus appear for BITS, PRTY (Parity) and
STOP (Stop Bits). Set each one to the desired setting using the t andu buttons.
CLX Modbus (8/06)
Rev. 1.2
5
4.0 The Modbus RS-485 Output & Commands Implemented
The default communication parameters are 8 bits, no parity and 1 stop bit. Please note that
all Modbus communication is via RS-485. The instruments can support a two wire
multidrop network of 255 units. If the connection is to the master on USB, an RS-485 to
USB converter is required.
4.1 Coils
These single-bit values are readable and changeable from the master. The data will be returned
with the lowest addressed coil in the LSB of the data. Unused bits in the data will be set to 0. True
is a 1 and False is 0.
4.1.1 Valid Command(s)
Code Name Broadcast
0x01 Read Coil Status No
0X05 Force Single Coil Yes
4.1.2 Format
16-bit word format
MSB LSB
Bit 15 Bit 14 Bit 13 Bit 12 Bit 11 Bit 10 Bit 9 Bit 8 Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
4.1.3 Valid Addresses
00001 – 00XXX
4.1.4 Definitions
Address Function Default
00001 Access code enabled False
00002 RS-485 enabled True
00003 4-20 mA enabled False
CLX Modbus (8/06)
Rev. 1.2
6
4.2 Input Status
These single-bit values are readable from the master. The data will be returned with the lowest
addressed input status in the LSB of the data. Unused bits in the data will be set to 0.
4.2.1 Valid Command(s)
Code Name Broadcast
0x02 Read Input Status No
4.2.2 Format
16-bit word format
MSB LSB
Bit 15 Bit 14 Bit 13 Bit 12 Bit 11 Bit 10 Bit 9 Bit 8 Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
4.2.3.Valid Addresses
10001 – 10XXX
4.2.4 Definitions
Address Function Default
10001 Instrument error False
10002 Instrument error with alarm (levels 1,2and 3) False
10003 Alarm 1 active False
10004 Alarm 2 active False
CLX Modbus (8/06)
Rev. 1.2
7
4.3 Holding Registers
These 16-bit values are readable and changeable from the master. The data is stored and
transmitted with the MSB first and then the LSB.
4.3.1 Valid Command(s)
Code Name Broadcast
0x03 Read Holding Registers No
0x06 Preset Single Register Yes
0X16 Preset Multiple Registers Yes
4.3.2 Format
Float – stored in two consecutive addresses, with the first address containing the least significant
word (lower part of mantissa) and the second address containing the most significant word (sign,
exponent, and upper part of mantissa).
4.3.3 Valid Addresses
40001 – 40XXX
4.3.4 Definitions
Address Type Register Min Default Max Function
40001 Int Decimal places 0 2 3 0 – XXXXX
1 – XXXX.X
2 – XXX.XX
3 – XX.XXX
40002 Int Units (scaling) 0 0 1 0 – PPM
1 – MG/L
40003 Int Response speed 1 10 60 Time constant (minutes)
40004 Int LCD backlight 1 8 10 Higher is brighter
40005, 40006 Float 4-20 mA
minimum value
0.0 0.00 10.0 Scaling value
40007, 40008 Float 4-20 mA
maximum value
0.0 6.00 10.0 Scaling value
40009 Int 4-20 mA error
alarm output
0 2 3 0 – Off
1 – 0 mA
2 – 2 mA
3 – 4 mA
40010 Int RS-485 baud 0 3 4 0 – 1,200
1 – 2,400
2 – 4,800
3 – 9,600
4 – 19,200
40011 Int RS-485 data bits 0 1 1 0 – 7 bits
1 – 8 bits
40012 Int RS-485 parity 0 0 2 0 – None
1 – Even
2 -- Odd
CLX Modbus (8/06)
Rev. 1.2
8
Address Type Register Min Default Max Function
40013 Int RS-485 stop bits 0 0 1 0 – One
1 -- Two
40014 Int Instrument
address
1 1 255
40015 Int Modbus serial
mode
0 0 1 0 – RTU
1 – ASCII
40016 Int Alarm 1 type 0 0 2 0 – Off
1 – Low alarm
2 – High alarm
3 – Error alarm
40017, 40018 Float Alarm 1 set point 0.0 1.0 10.0
40019 Int Alarm 2 type 0 0 2 0 – Off
1 – Low alarm
2 – High alarm
3 – Error alarm
40020, 40021 Float Alarm 2 set point 0.0 1.0 10.0
40022, 40023 Unused
40024 Int Measurement
period
90 150 600 Seconds between
measurements
40025 Int Response speed 0 10 30 Response time constant,
in minutes
40026 Unused
CLX Modbus (8/06)
Rev. 1.2
9
4.4 Input Registers
These 16-bit values are readable by the master. The data is stored with the MSB first and then the
LSB.
4.4.1 Valid Command(s)
Code Name Broadcast
0x04 Read Input Registers No
4.4.2 Format
Float – stored in two consecutive addresses, with the first address containing the least significant
word (lower part of mantissa) and the second address containing the most significant word (sign,
exponent, and upper part of mantissa).
4.4.3 Valid Addresses
30001 – 30XXX
4.4.4 Definitions
Address Type Register Value Function
30001, 30002 Float Sensor reading -- The meter reading
30003, 30004 Float Sensor reading raw -- Sensor reading to six significant places
30005 Int Version major -- Software version major number
30006 Int Version minor -- Software version minor number
30007 Int Version revision -- Software version revision number
30008 Int Model number -- Product number
30009 Int Model suffix number -- Options – model dependent
0 unknown
1 normal
2 Over range
3 Under range
4 need standard
5 need sample
30010 Int Reading status
6
reading problem (Err)
30011 Int Days since last prime -- No.of days since the last prime was performed
0 Revision 1 30012 Int PCB Revision
1 Revision 2
0x0000 normal
0x0001 Error
0x0002 Alarm 1 is active
0x0004 Alarm 2 is active
30013 Int Instrument error
summary (bit-mapped)
0x0008 Calibration error
0x00000 Normal
0x00001
Alarm 1 active (ALM1)
0x00002
Alarm 2 active (ALM2)
0x00004
Data over-range (OVER)
30014, 30015 Long Level 4 Errors (bit-
mapped), least severe
0x00008
Reading error (Err)
CLX Modbus (8/06)
Rev. 1.2
10
0x00000 Normal
0x00001
Break in the 4-20 mA current loop (MA)
0x00002
Calibration error (ZCAL)
0x00004
No intake water (WATR)
0x00008
Intake water fill fast (FAST)
0x00010
Intake water fill slow (SLOW)
0x00020
Purge is slow (PURG)
0x00040
Purge clogged (NPRG)
0x00080
Cannot determine intake water level (H2O)
0x00100
Intake solenoid stuck open (ISOL)
0x00200
Purge solenoid stuck closed (PSOL)
0x00400
Problem with reagent (RGNT)
0x00800
Sample chamber glass too dark (GLAS)
0x01000
Water calibration invalid (WCAL)
0x02000
Reagent is old and needs to be replaced (REPL)
30016, 30017 Long Level 3 Errors (bit-
mapped)
0x04000
Adjust calibration error (ACAL)
0x00000 Normal
0x00001
POST error (POST)
0x00002
Visible lamp blown (GRN0)
0x00004
Visible lamp stuck on (GRN1)
0x00008
Visible lamp optimization problem (GRN2)
0x00010
IR lamp blown (WTR0)
0x00020
IR lamp stuck on (WTR1)
0x00040
IR lamp optimization problem (WTR2)
0x00080
Solenoid power supply (SOL0)
0x00100
Intake solenoid (SOL1)
0x00200
Purge solenoid (SOL2)
30018, 30019 Long Level 2 Errors (bit-
mapped)
0x00400
Reagent solenoid (SOL3)
0x00000 Normal
0x00001 MSP oscillator
0x00002 MSP A/D
0x00004 MSP flash data read
0x00008 MSP flash data write
0x00010 A/D problem
0x00020 S/W MiCOS queue overflow
0x00040 S/W stack overflow
0x00080 S/W invalid PWM port
0x00100 S/W options missing
30020, 30021 Long Level 1 Errors (bit-
mapped), most severe
0x00200 S/W sensor type option
CLX Modbus (8/06)
Rev. 1.2
11
Note: Error messages shown in Prentiss and in (Italics)
4.5 Exception Responses Implemented
Code Name Meaning
00 -- No error
01 ILLEGAL FUNCTION The function code is not allowed in the device.
02 ILLEGAL DATA ADDRESS The data address is not allowed in the device
03 ILLEGAL DATA VALUE A value contained in the query field is wrong for the device
CLX Modbus (8/06)
Rev. 1.2
12
5.0 Warranty
HF scientific, inc., as vendor, warrants to the original purchaser of this instrument that it
will be free of defects in material and workmanship, in normal use and service, for a
period of one year from date of delivery to the original purchaser. HF scientific, inc.’s,
obligation under this warranty is limited to replacing, at its factory, the instrument or any
part thereof. Parts, which by their nature are normally required to be replaced
periodically, consistent with normal maintenance, specifically reagent, desiccant, sensors,
electrodes and fuses are excluded. Also excluded are accessories and supply type items.
Original purchaser is responsible for return of the instruments, or parts thereof, to HF
scientific, inc.’s factory. This includes all freight charges incurred in shipping to and from
HF scientific, inc.’s factory.
HF scientific, inc. is not responsible for damage to the instrument, or parts thereof,
resulting from misuse, environmental corrosion, negligence or accident, or defects
resulting from repairs, alterations or installation made by any person or company not
authorized by HF scientific, inc.
HF scientific, inc. assumes no liability for consequential damage of any kind, and the
original purchaser, by placement of any order for the instrument, or parts thereof, shall be
deemed liable for any and all damages incurred by the use or misuse of the instruments, or
parts thereof, by the purchaser, its employees, or others, following receipt thereof.
Carefully inspect this product for shipping damage, if damaged, immediately notify the
shipping company and arrange an on-site inspection. HF scientific, inc. cannot be
responsible for damage in shipment and cannot assist with claims without an on-site
inspection of the damage.
This warranty is given expressly and in lieu of all other warranties, expressed or implied.
Purchaser agrees that there is no warranty on merchantability and that there are no other
warranties, expressed or implied. No agent is authorized to assume for HF scientific, inc.
any liability except as set forth above.
HF scientific, inc.
3170 Metro Parkway
Fort Myers, Florida 33916-7597
Phone: (239) 337-2116
Fax: (239) 332-7643
CLX Modbus (8/06)
Rev. 1.2
13
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